Answer:
3.2 J
Step-by-step explanation:
It is convenient to use newtons and meters for the units when calculating work.
The spring constant (k) is ...
k = (30 N)/(15 cm -12 cm) = (30 N)/(.03 m) = 1000 N/m
For some displacement d, the work done in stretching the spring is ...
W = (1/2)kd^2 = (1/2)(1000 N/m)(.08 m)^2 = (1/2)(1000)(.0064) Nm
= 3.2 J
3.2 joules of work is done stretching the spring.
